Reduced Kapitza resistance microwave filter for cryogenic environments

ABSTRACT

An architecture for, and techniques for fabricating, a thermal decoupling device are provided. In some embodiments, thermal decoupling device can be included in a thermally decoupled cryogenic microwave filter. In some embodiments, the thermal decoupling device can comprise a dielectric material and a conductive line. The dielectric material can comprise a first channel that is separated from a second channel by a wall of the dielectric material. The conductive line can comprise a first segment and a second segment that are separated by the wall. The wall can facilitate propagation of a microwave signal between the first segment and the second segment and can reduce heat flow between the first segment and the second segment of the conductive line.

TECHNICAL FIELD AND BACKGROUND

The subject disclosure generally relates to microwave filter componentswith segmented or discontinuous signal conductors that, in a cryogenicenvironment where temperatures are very low, exhibit reduced Kapitzaresistance.

Quantum computing is generally the use of quantum-mechanical phenomenafor the purpose of performing computing and information processingfunctions. Quantum computing can be viewed in contrast to classicalcomputing, which generally operates on binary values with transistors.That is, while classical computers can operate on bit values that areeither 0 or 1, quantum computers operate on quantum bits that comprisesuperpositions of both 0 and 1, can entangle multiple quantum bits, anduse interference.

Hence, a fundamental element of quantum computing is the quantum bit(qubit). A qubit represents a quantum mechanical system whereinformation can be encoded and manipulated. A significant aspect of aqubit is coherence time, which represents how long a quantum state ofthe qubit can be maintained.

A successful implementation of quantum computing will likelyexponentially extend the computing power of current computationalsystems, having the potential to revolutionize numerous technologicalfields. Today, there are many suggested approaches to implementing aquantum computing device. One of the most feasible approaches toimplementation of a quantum computing architecture is based onsuperconducting devices, which are typically implemented in a cryogenicenvironment. A cryogenic environment can be one with very low pressure(e.g., a vacuum or near-vacuum) and very low temperature. For example, acryogenic environment may exhibit temperatures below about 100 degreesKelvin (K) and can be as low as about 10 millikelvin (mK) or less, suchas in a superconducting based quantum computing environment.

The performance of any superconducting based quantum computingarchitecture is heavily depended on the quality of the superconductingquantum bits (e.g., qubits), which can be directly characterized by themeasuring coherence times and qubit errors. These coherence times andqubit errors strongly depend on the performance of microwave hardware(e.g., filter devices) at low temperatures.

While microwave filters do exist, even some that are commerciallyadvertised to be suitable for cryogenic environments, existing microwavefilters do not appear to be designed or tested to operate attemperatures lower than 77 K, not to mention the temperatures (e.g.,near or below 10 mK) that might accompany a superconducting basedquantum computing implementation.

Hence, a technical problem arises in the field of quantum computing inthat, at certain cryogenic temperatures (e.g., below about 77 K),existing microwave frequency filters or attenuators can behave inunexpected ways. For example, elements of a microwave filter orattenuator, in a cryogenic environment, may become superconductive, andno longer function to pass, filter, or attenuate the signal based onfrequency. The inventors have identified that these technical problemarises due at least in part to two distinct technical problems.

A first technical problem arises due to the fact that signal conductorssuch as coaxial cables or other hardware cross numerous temperaturezones, typically spanning from room temperature environments tocryogenic environments. Hence, the elements of the signal conductor,which can include a conductive line to propagate the signals as well asa dielectric sheath or substrate, can have dramatic temperaturedifferences. For example, a conductive line employed to propagate asignal from a room temperature environment to a cryogenic environmentmay vary in temperature by 300 K. The inventors have identified thatsuch significant temperature differences between different portions ofthe conductive line propagating a signal can cause thermal noiseresulting from thermal flow or the exchange of heat between one portionof the conductive line to another portion of the conductive line. Thisthermal noise can degrade the performance of microwave hardware, whichcan in turn degrade qubit performance.

While the first technical problem relates to difficulties encountereddue to heat flow within a single material (e.g., the conductive line), asecond distinct technical problem arises due to difficulties associatedwith heat flow between different materials. The second technical problemarises due to a phenomenon known as Kapitza resistance, which tends tobe negligible at room temperature or above cryogenic temperatures butcan become very significant at cryogenic temperatures. Kapitzaresistance refers to a thermal resistance effect at a boundary betweendifferent materials in the presence of a heat flux. In other words,Kapitza resistance can prevent various materials within a lowtemperature environment from settling at a uniform temperature.

For example, suppose an ambient temperature and/or the temperature fluxacross the interface between the two materials in a cryogenicrefrigerator is 10 mK. Microwave hardware within that environment cancomprise a conductive line formed in a dielectric, where theelectrically conductive line can provide filtering, for instance bypassing or attenuating the microwave signal based on frequency. Thedielectric might be cooled to 10 mK. However, the conductive line, whichin operation may represent a source of heat, may not effectivelytransfer heat from the conductive line to the dielectric due in part tothe Kapitza resistance phenomenon. Thus, the conductive line mightremain at a temperature significantly higher than the ambientenvironment and/or the dielectric in which the conductive line issituated. The inventors have identified that a temperature differencebetween the dielectric and the conductive line can cause variousproblems such as low frequency noise, unexpected behavior, and others,any one of which can negatively impact the quality of qubits (e.g.,coherence times and qubit errors) of a quantum computing device thatrelies on the microwave hardware.

A third technical problem arises due to an inability to thermalize theconductive line, which can be a source of heat in the system. The thirdtechnical problem can arise due to various materials used to implementthe microwave hardware exhibiting insufficient thermal conductivitybetween two different materials such as between the conductive line andthe dielectric. Traditionally, dielectric materials and conductivematerials are selected based on electrical properties and cost, withlittle or no consideration for thermal properties.

SUMMARY

The following presents a summary to provide a basic understanding of oneor more embodiments of the invention. This summary is not intended toidentify key or critical elements, or delineate any scope of theparticular embodiments or any scope of the claims. Its sole purpose isto present concepts in a simplified form as a prelude to the moredetailed description that is presented later. In one or more embodimentsdescribed herein, systems, methods, apparatus and/or products aredescribed that facilitate at least one of reduced thermal flow within amaterial or facilitate reduced Kapitza resistance at a boundary betweentwo different materials.

According to an embodiment of the present invention, a thermaldecoupling device can be provided. The thermal decoupling device cancomprise a dielectric material. The dielectric material can comprise afirst channel that is separated from a second channel by a wall of thedielectric material. The thermal decoupling device can further comprisea conductive line. The conductive line can comprise a first segment anda second segment that are separated by the wall. The wall can facilitatepropagation of a microwave signal between the first segment and thesecond segment and can reduce heat flow between the first segment andthe second segment of the conductive line. An advantage provided by thisthermal decoupling device can be reduced thermal noise due to heat flowwithin the conductive line that spans multiple temperature zones. Insome embodiments, the first and second channels can be arranged in apattern that facilities a filter operation on a microwave signalpropagated in a cryogenic environment having a temperature below about77 degrees Kelvin. An advantage of this arrangement is that the thermaldecoupling device can be integrated into a filter device providing athermally decoupled filter device.

According to an embodiment of the present invention, a thermallydecoupled cryogenic microwave filter device can be provided. Thethermally decoupled cryogenic microwave filter device can comprise adielectric having discontinuous channels in a pattern that facilitates afilter operation on a microwave signal propagated in a cryogenicenvironment having a temperature below about 77 degrees Kelvin (K). Thediscontinuous channels can comprise a first channel that is separatedfrom a second channel by a wall of the dielectric. The thermallydecoupled cryogenic microwave filter device can further comprise aconductive line. The conductive line can comprise a first segment,situated in the first channel, and a second segment, situated in thesecond channel. The first and second segments can be separated by thewall. The wall can facilitate propagation of the microwave signalbetween the first segment and the second segment and can reduce heatflow between the first segment and the second segment of the conductiveline. An advantage provided by this thermally decoupled cryogenicmicrowave filter device can be improved performance at very lowtemperatures such as temperatures associated with a cryogenicenvironment in which a quantum computing architecture can beimplemented. For example, heat flow within a conductive line can causethermal noise. Such can be mitigated by thermally decoupling varioussegments of a discontinuous conductive line. In some embodiments, thewall can have dimensions determined to propagate the microwave signalbased on the microwave signal having a frequency above about onegigahertz (GHz). An advantage provided is that even though theconductive line is discontinuous, and therefore may not be suitable fordirect current applications, signals with sufficiently high frequencycan be propagated between the discontinuous segments of the conductiveline.

According to an embodiment of the present invention, a method can beprovided. The method can be, e.g., a method for fabricating a thermaldecoupling device. The method can comprise forming, by a fabricationdevice, discontinuous channels in a dielectric. The discontinuouschannels can have a pattern comprising a first channel that is separatedfrom a second channel by a wall of the dielectric material. The methodcan further comprise, forming, by the fabrication device, a conductiveline in the discontinuous channels of the dielectric material. Theconductive line can comprise a first segment and a second segment. Thefirst segment and the second segment can be separated by the wall thatfacilitates propagation of a microwave signal between the first segmentand the second segment and reduces heat flow between the first segmentand the second segment of the conductive line. An advantage provided bythis method can be reduced thermal noise due to heat flow within theconductive line that spans multiple temperature zones. In someembodiments, the forming the conductive line can comprise sintering aconductive material in the discontinuous channels. An advantage providedby sintering the conductive line can be that Kapitza resistance betweenthe conductive line and the substrate can be reduced due to increasedsurface contact area between the conductive line and the substrate.

According to an embodiment of the present invention, a method can beprovided. The method can be, e.g., for fabricating a thermally decoupledcryogenic microwave filter. The method can comprise forming, by afabrication device, a dielectric that operates as an electricalinsulator and a thermal conductor at cryogenic temperatures below about77 degrees Kelvin (K). The dielectric can comprise a material having athermal conductivity that is above about 200 watts per meter-Kelvin(W/m-K) at 77 K. The method can further comprise forming, by thefabrication device, discontinuous channels in the dielectric. Thediscontinuous channels can be formed in a pattern that facilitates afilter operation on a microwave signal propagated in the cryogenicenvironment. The discontinuous channels can comprise a first channel anda second channel separated by a wall of the dielectric. Further still,the method can comprise, sintering, by the fabrication device, aconductive material in the discontinuous channels having the pattern.Such can result in a conductive line comprising a first segment and asecond segment that are separated by the wall that facilitatespropagation of the microwave signal through the conductive line andreduces heat flow between the first segment and the second segment ofthe conductive line. An advantage provided by this method can be reducedthermal noise along the conductive line. Another advantage can bereduced Kapitza resistance between the conductive line and thedielectric. Reduction of thermal noise and reduction of Kapitzaresistance can lead to improved performance at very low temperaturessuch as temperatures associated with a cryogenic environment in which aquantum computing architecture can be implemented. For example, Kapitzaresistance can be reduced by increasing surface contact area between theconductive line and the substrate. Sintering the conductive line canresult in an increased surface contact area between the conductive lineand the substrate.

According to an embodiment of the present invention, a thermaldecoupling product formed by a process can be provided. The process cancomprise forming, by a fabrication device, a first channel that isseparated from a second channel by a wall of the dielectric material.The process can further comprise forming, by the fabrication device, aconductive line. The conductive line can comprise a first segment,formed in the first channel, and a second segment, formed in the secondchannel. The first segment and the second segment can be separated bythe wall. The wall can allow propagation of a microwave signal betweenthe first segment and the second segment and reduces heat flow betweenthe first segment and the second segment of the conductive line. Anadvantage provided by this process can result in a thermal decouplingproduct that can, via discontinuous segments of the conductive line,reduce heat flow between the various discontinuous segments of theconductive line. Reducing the heat flow can result in less thermal noiseassociated with the conductive line, which can provide an improvedsignal.

DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a diagram of a conductive line that physicallyextends through numerous temperature environments in accordance with oneor more embodiments.

FIG. 2 illustrates a block diagram of a thermal decoupling device thatcan propagate a signal while reducing heat flow in accordance with oneor more embodiments.

FIG. 3 illustrates a block diagram of a thermally decoupled cryogenicmicrowave filter device that can propagate a signal while reducing heatflow in accordance with one or more embodiments.

FIG. 4 illustrates a block diagram of system and an overlaid temperaturegraph illustrating effects of Kapitza resistance in accordance with oneor more embodiments.

FIG. 5 illustrates a block diagram of cryogenic environmentdemonstrating problematic results of Kapitza resistance in accordancewith one or more embodiments.

FIG. 6 illustrates a graphical depiction of an example, non-limitingthermally decoupled cryogenic microwave filter having reduced Kapitzaresistance in accordance with one or more embodiments.

FIG. 7 illustrates a block diagram of an example housing for thecryogenic microwave filter in accordance with one or more embodiments.

FIGS. 8-10 illustrate a process by which a thermal decoupling product ora suitable thermally decoupled cryogenic microwave filter product can beproduced in accordance with one or more embodiments.

FIG. 11 illustrates a flow diagram of an example, non-limiting methodfor fabricating a thermal decoupling device in accordance with one ormore embodiments.

FIG. 12 illustrates a flow diagram of an example, non-limiting methodfor fabricating a thermally decoupled cryogenic microwave filter inaccordance with one or more embodiments.

FIG. 13 illustrates a flow diagram of an example, non-limiting methodfor sintering a conductive material in accordance with one or moreembodiments.

FIG. 14 illustrates a flow diagram of an example, non-limiting methodfor fabricating a housing for a cryogenic microwave filter in accordancewith one or more embodiments.

FIG. 15 illustrates a block diagram of an example, non-limitingoperating environment in which one or more embodiments described hereincan be facilitated.

DETAILED DESCRIPTION

The following detailed description is merely illustrative and is notintended to limit embodiments and/or application or uses of embodiments.Furthermore, there is no intention to be bound by any expressed orimplied information presented in the preceding Background or Summarysections, or in the Detailed Description section.

As has been noted above, subject matter disclosed herein can addressdistinct technical problems. For example, a first technical problemarises due to thermal noise that results from heat flow within a singlematerial that spans multiple temperature zones, which is primarilydiscussed in connection with FIGS. 1-3 of this disclosure. A secondtechnical problem arises due to Kapitza resistance that operates atinterfaces between two different materials, which is primarily discussedin connection with FIGS. 4-6 of this disclosure.

Turning now to the drawings, with initial reference to FIG. 1 , adiagram is illustrated of a conductive line 100 that physically extendsthrough numerous temperature environments in accordance with one or moreembodiments. Conductive line 100 is illustrated as a continuous line orpiece of wire that can be utilized to convey a signal between cryogenicenvironment 102 and lab environment 104. Portions of conductive line 102may be embodied as a coaxial cable or another suitable configuration.Conductive line 100 may be employed in connection with a superconductingquantum computing device, which is typically implemented in cryogenicenvironment 102, where temperatures are very low.

Cryogenic environment 102 can be implemented inside a cryogenicrefrigerator that can have multiple stages, with each stage exhibitingdifferent temperatures. Thus, within cryogenic environment 102, somepositive integer, N, temperature zones can exist. As illustrated, thecore of cryogenic environment 102, representing temperature zone 0, canbe very close to absolute zero an example of which can be 10 millikelvin(mK). Other stages of cryogenic environment 102 can exhibit differenttemperatures ranging from about 10 mK to about 100 K. Beyond cryogenicenvironment 102, such as outside the cryogenic refrigerator, the ambienttemperature, illustrated as temperature zone R, can be room temperature,which may be near 300 K.

Thus, conductive line 100 used to relay signals between the core ofcryogenic environment 102 and lab environment 104 may operate not onlyas current path but as a heat path as well. For example, a directcurrent path typically relies on a continuous conductive line (e.g.,conductive line 100), but a continuous conductive line is also aneffective thermal path. As illustrated, heat will tend to flow intoconductive line 100 at areas in temperature zone R, while flowing out ofconductive line 100 at areas in temperature zones 0-N. In effect, heatwill significantly tend to flow toward temperature zone 0.

The inventors have observed that such heat flow can cause thermal noise,which can negatively affect the quality of a signal being conveyed byconductive line 100 or negatively affect devices served by conductiveline 100. For example, the thermal noise can reduce the performance of afilter device or reduce the quality of a superconductive qubit of aquantum computing device. Hence, thermal noise represents a technicalproblem. Mitigating this thermal noise can improve performance of filterdevices, quantum computing devices, and other devices or systems. Atechnique to reduce or mitigate thermal noise resulting from heat flowwithin a conductive line can be found in connection with FIG. 2 .

With reference now to FIG. 2 , a block diagram of thermal decouplingdevice 200 is illustrated that can propagate a signal while reducingheat flow in accordance with one or more embodiments. Repetitivedescription of like elements employed in other embodiments describedherein is omitted for sake of brevity. Such can be accomplished bysegmenting a conductive line into two or more discontinuous segments.

For example, thermal decoupling device 200 can comprise dielectricmaterial 202, which can be a sheath, conduit, or substrate depending onimplementation. Dielectric material 202 can be any suitable material,although certain materials or properties can be favored, such as areduced Kapitza resistance property further detailed in connection withFIG. 6 . Dielectric material 202 can comprise a first channel that isseparated from a second channel by a wall 204 of the dielectric material202. The first channel and the second channel can be filled or occupiedby discontinuous segments of a conductive line 206, as detailed below.In some embodiments, the first channel and the second channel can extendin directions that are substantially parallel. By proxy, a first segmentand a second segment of the conductive line can extend in directionsthat are substantially parallel.

Wall 204 is depicted in dark grey to illustrate a separation between thefirst channel and the second channel, while the remainder of dielectricmaterial 202 is illustrated in light grey. In some embodiments, wall 204can be substantially identical to, or have substantially similarproperties as, dielectric material 202. In some embodiments, wall 204can be composed of a different material having different properties thandielectric material 202.

Thermal decoupling device 200 can further comprise conductive line 206.Rather than being a continuous conductive line employed in othersystems, conductive line 206 can be discontinuous or segmented. Forexample, conductive line 206 can comprise first segment 206A and secondsegment 206B, which can respectively occupy the first channel and thesecond channel of dielectric material 202. Hence, first segment 206A andsecond segment 206B can be separated by wall 204. Wall 204 can beconfigured to facilitate propagation of a signal 208 between firstsegment 206A and second segment 206B and reduce heat flow between firstsegment 206A and second segment 206B.

According to standard models, signals (e.g., signal 208) can propagatethrough a conductor (e.g., conductive line 206) via a flow of electrons.If these electrons are in a relatively low energy state, which istypical for direct current (DC) applications, a continuity of theconductor is relied on to convey signal 208. Thus, it can be readilyobserved that signal 208 can be propagated through first segment 206A.Signal portion 208A illustrates signal 208 being propagated throughfirst segment 206A. However, for DC-type applications, signal 208 maynot be capable of flowing to second segment 206B due to thediscontinuity in conductive line 206 caused by wall 204.

However, at high frequencies, such as frequencies within a microwavespectrum, signal 208 can cause the electrons of conductive line 206 tobecome excited, representing a higher energy state. In this higherenergy state, electrons can jump from one conductor to another conductorin sufficient proximity. In other words, wall 204 effectively operatesas a capacitor and signal 208 can be conveyed from first segment 206A tosecond segment 206B, which is illustrated by signal portion 208B. Oncepassed wall 204, signal 208 can be conveyed along second segment 206B,which is illustrated by signal portion 208C

The microwave spectrum is generally considered to be from about 300megahertz (MHz) to about 300 gigahertz (GHz). Depending on variousfactors, including the dimensions of wall 204, lower frequencies maysufficiently excite electrons to cause the above-described effect. Thus,signal 208 is not necessarily limited to frequencies at or above themicrowave spectrum, but such is a suitable threshold for many technicalapplications.

For typical quantum computing applications or for cryogenic frequencyfilters or other hardware, signal 208 will typically have a frequencyabove about one GHz. Hence, in some embodiments, wall 204 can havedimensions determined to propagate signal 208 having a frequency aboveabout one GHz. Although many dimensions are suitable, as one example, athickness (e.g., a distance between first segment 206A and secondsegment 206B) of wall 204 can be about 0.6 millimeters. Such a thicknesscan allow signal 208 to propagate between first segment 206A and secondsegment 206B, yet still reduce heat flowing between first segment 206Aand second segment 206B, which is illustrated by reference numeral 210.However, it is understood that other dimensions can be suitable and suchcan vary based on implementation. Such will typically be in a rangebounded by a maximum thickness for which a given signal 208 can passwall 204, which is heavily influenced by the frequency of signal 208,and a minimum thickness that still sufficiently reduces heat flowbetween first segment 206A and second segment 206B, which is heavilyinfluenced by the materials or thermal properties of wall 204.

Recall that conductive line 206 might extend through many differenttemperature zones, potentially ranging from about 300 K to less than 1K. Hence, substantial portions of first segment 206A and second segment206B might be in different temperature zones, which can result in athose two segments having markedly different temperatures. However, heatflow within conductive line 206 can be limited within a given segment,which can reduce thermal noise. In this example, much of the displayedportions of first segment 206A is in temperature zone 1, while theentirety of the displayed portions of second segment 206B is intemperature zone 0. Thus, first segment 206A can exhibit a first meantemperature that is higher than a second mean temperature of secondsegment 206B. In some embodiments, first segment 206A can stably remainat a different temperature than second segment 206B, while signal 208can still be propagated between the two.

In effect, first segment 206A and second segment 206B can be thermallydecoupled by thermal decoupling device 200. Heat can be free to flowwithin a given segment, but heat flow between two different segments canbe reduced. As one advantage, given that heat flow can be reduced bywall 204, thermal noise resulting from such heat flow through conductiveline 206 can be significantly reduced. As another advantage, operationof the associated cryogenic refrigerator device can be more efficient ormore effective, since a continuous flow path from room temperature zonesto the core of the cryogenic environment has been removed by segmentingconductive line 206.

Turning back to FIG. 1 , it can be appreciated that thermal decouplingdevice 200 can be advantageously implemented at the boundaries betweenvarious temperature zones of cryogenic environment 102 such as at theboundaries between various stages of an associated cryogenicrefrigerator. For example, consider one or more thermal decouplingdevice 200 situated at a boundary between temperature zone N (e.g., 100K) and temperature zone R (e.g., 300 K). A first segment of conductiveline 100 situated in temperature zone N need not be exposed to heat flowfrom a second segment of conductive line 100 that is situated intemperature zone R. Rather, the first segment can find some thermalequilibrium at or near 100 K, while the second segment can find somethermal equilibrium at or near 300. However, the signal can still bepropagated between the first segment and the second segment. Anotheradvantage of thermal decoupling device 200 can be used in connectionwith filter devices, an example of which is detailed with reference toFIG. 3 .

Turning now to FIG. 3 , a block diagram of thermally decoupled cryogenicmicrowave filter device 300 is illustrated that can propagate a signalwhile reducing heat flow in accordance with one or more embodiments.Repetitive description of like elements employed in other embodimentsdescribed herein is omitted for sake of brevity. For example, thermallydecoupled cryogenic microwave filter device 300 can comprise one or morethermal decoupling devices 200.

In that regard, thermally decoupled cryogenic microwave filter device300 can comprise dielectric 302. Dielectric 302 can have discontinuouschannels in a pattern 306 that facilitates a filter operation on amicrowave signal propagated in a cryogenic environment having atemperature below about 77 degrees Kelvin. The discontinuous channelscan have a first channel that is separated from a second channel by awall 308 of dielectric 302, an example of which is depicted at FIG. 2 .

Thermally decoupled cryogenic microwave filter device 300 can furthercomprise conductive line 304 that can have multiple discontinuoussegments. For instance, conductive line 304 can comprise a first segment304A, situated in the first channel, and a second segment 304B, situatedin the second channel, separated by wall 308. Wall 308 can facilitatepropagation of microwave signal through conductive line 304 such asthrough multiple segments of conductive line 304. Wall 308 can furtherreduce heat flow between first segment 304A and second segment 304B.Hence, various segments of conductive line 304 can be thermallydecoupled, which advantageously can reduce or mitigate thermal noise.Techniques associated with reducing effects of Kapitza resistance cannow be described, beginning with FIG. 4 .

Referring now to FIG. 4 , a block diagram of system 400 and an overlaidtemperature graph illustrating effects of Kapitza resistance inaccordance with one or more embodiments. Repetitive description of likeelements employed in other embodiments described herein is omitted forsake of brevity. System 400 can comprise two different materials thatshare a boundary interface 402, where one material has contact with theother material. Hence, in this example, material A contacts material Bat boundary interface 402. It is assumed in this example that thesematerials, or the interface between the two materials is subject to acommon temperature flux and/or the ambient temperature is the same forboth, call it T0. It is further assumed that material A has an initialtemperature, T1, and material B has an initial temperature T2 that islower than T1.

At room temperature, where the effects of Kapitza resistance tend to benegligible, material A and material B will likely settle to a commontemperature, as heat flows through boundary interface 402 from materialA to material B. However, at cryogenic temperatures, where the effectsof Kapitza resistance can be much more significant, thermal boundaryresistance, R, creates a temperature drop, ΔT, across boundary interface402. In other words, the thermal boundary resistance prevents some heatexchange between material A and material B such that material A andmaterial B do not settle to a common temperature.

It is believed this temperature mismatch results due to scattering ofenergy carriers such as phonons or electrons at boundary interface 402.The probability that an energy carrier scatters at boundary interface402 instead of transferring heat through the boundary is a function ofthe energy states of the materials on both sides of boundary interface402. At cryogenic temperatures, these energy states are lower, yieldinga much higher probability of scattering. It has been observed that atlow temperatures, such as cryogenic temperatures, the phenomenon ofKapitza resistance, also known as thermal boundary resistance, resultsin a significant temperature drop, ΔT at boundary interface 402 thatserves as a boundary between two different materials. It is furtherobserved that this temperature drop, ΔT, can lead to technical problemsthat are further detailed in connection with FIG. 5 .

With reference now to FIG. 5 , a block diagram of cryogenic environment500 demonstrating problematic results of Kapitza resistance inaccordance with one or more embodiments. Repetitive description of likeelements employed in other embodiments described herein is omitted forsake of brevity. Cryogenic environment 500 may exhibit a very lowpressure or be a vacuum. Cryogenic environment 500 may be refrigeratedto a very low temperature such as less than about 77 K, and might infact be below 4 K, and in some cases 10 millikelvin or less. Withincryogenic environment 500 can be some portion of quantum computingarchitecture 502.

Quantum computing architecture 502 can comprise various microwavehardware 504 such as, for instance, a microwave frequency filter orattenuator. For example, a microwave frequency filter can be employedfor controlling a superconducting qubit of quantum computingarchitectures 502. The internal structure of the microwave frequencyfilter can comprise a conductive line situated in a dielectric. Hence,the conductive line shares various instances of boundary interface 506with the dielectric, which can be similar to that described inconnection with material A and material B in FIG. 1 . Assuming thetemperature flux across boundary interface 506 is T0, conductive line isat T1, and dielectric is at T2, then Kapitza resistance can cause atemperature drop, ΔT, across boundary interface 506. Put differently,the conductive line is not thermalized and maintains a temperature thatis higher by ΔT than the dielectric. It has been observed thattemperature differences between the conductive line and dielectric cancause microwave hardware 504 to behave unexpectedly. For example, thistemperature difference can result in low frequency noise or otherdegraded performance of microwave hardware 504. Such can lead to shortercoherence times, increased qubit errors, or other degraded performanceof quantum computing architecture 502. In some instances, elements(e.g., the conductive line) of microwave hardware 504 might becomesuperconductive at very low temperatures, in which case the microwavehardware 504 may not function as intended.

A potential solution to the aforementioned technical problems caused byKapitza resistance at boundary interface 506 can be effectuated byvarious techniques to reduce Kapitza resistance at boundary interface506. Such a reduction in the thermal boundary resistance can result in alower value of ΔT, which can avoid the degraded performance of microwavehardware 504 at very low temperatures.

FIG. 6 is a graphical depiction of an example, non-limiting cryogenicmicrowave filter 600 having reduced Kapitza resistance in accordancewith one or more embodiments. Repetitive description of like elementsemployed in other embodiments described herein is omitted for sake ofbrevity. In some embodiments, cryogenic microwave filter 600 can beutilized to control a qubit of a superconducting quantum computingarchitecture.

Cryogenic microwave filter 600 can comprise substrate 602. Substrate 602can be formed of a dielectric material determined to have a desirablethermal property. For example, the material can be determined to have athermal conductivity that is above about 200 watts per meter-Kelvin(W/m-K) at a temperature of 77 degrees Kelvin (K). In some embodiments,the material can be a dielectric material that acts as an electricalinsulator. It is appreciated that materials for conventional substratesor dielectrics tend to be selected based on some function of price anddesired electrical properties such as being electrically insulating.Without identifying the increased significance of Kapitza resistance atcryogenic temperatures as well as the technical problems said Kapitzaresistance can cause in connection with filter devices, there is noapparent reason for filter designers to consider thermal conductivityproperties of a dielectric or substrate, particularly in the event thata given thermal conductivity property might increase the cost of adielectric or substrate without providing improved electricalproperties.

However, by selecting a material determined to have a high thermalconductivity, in this example above 200 W/m-K at 77 K, elements that arein contact with substrate 602 (e.g., conductive line 604) can be moreeffectively thermalized, which can reduce thermal noise. For instance,hot electrons can be more effectively removed from conductive line 604.Since DC signals are not propagated between various segments ofconductive line 604, noise associated with DC signals can be reduced oreliminated. A result of reduced noise can be improved performance ofassociated elements or systems. For example, an associated quantumcomputing system can realize improved coherence times and fewer qubiterrors when relying on cryogenic microwave filter 600 instead ofexisting microwave filters.

In some embodiments, the material selected for substrate 602 can besapphire. In some embodiments, the material selected for substrate 602can be diamond. Other materials are possible, provided such exhibitsufficient thermal conductivity. Both sapphire and diamond haveextremely high thermal conductivity, even when compared typical ceramicsubstrates such as alumina. For example, alumina, which is known to havea high thermal conductivity, but which is one of the most commonlyselected materials for a ceramic substrate and/or dielectric due to itslow cost and low electrical conductivity has a thermal conductivity of157 W/m-K at 77 K. By contrast, other materials such as sapphire anddiamond have significantly better thermal conductivity at cryogenictemperatures, which is illustrated in Table I.

TABLE I Thermal Conductivity (W/m-K) Material @ 77 K @ 20 K @ 10 K @ 4 KAlumina 157 24 5.2 0.49 Sapphire 1100 15700 29 230 Diamond 3400 1500 51067

Even though alumina is known to have a high thermal conductivityrelative to many other materials, such is typically not high enough,depending on the application. As illustrated in Table I, sapphire anddiamond exhibit a thermal conductivity at 77 K that is near to ten (inthe case of sapphire) or greater than twenty (in the case of diamond)times higher. At even lower temperatures, e.g., at 4 K, sapphire anddiamond can exhibit a thermal conductivity that is more than two ordersof magnitude higher than that for alumina. Thus, at cryogenictemperatures, a boundary interface between the substrate and a differentmaterial can be expected to have reduced Kapitza resistance and a lowerΔT when the substrate is composed of, e.g., sapphire or diamond thanwhen composed of more common materials such as alumina.

Cryogenic microwave filter 600 can further comprise conductive line 604.Conductive line 604 can be formed in a recess or multiple recesses ofsubstrate 602. Conductive line 604 can facilitate a filter operation ona microwave signal propagated in a cryogenic environment having atemperature below about 77 K.

In some embodiments, the filter operation facilitated by conductive line604 can be a function of a geometry of the recesses in substrate 602.For example, since conductive line 604 can be formed in these recessesor conductive line 604 can fill some portion of the recess, a pattern ofthe recesses can provide or facilitate the desired filtering operation.In this example, pattern 606 illustrates one example of a suitablegeometry. In some embodiments, the filter operation facilitated bypattern 606 can be a bandpass filter operation, where frequencies of themicrowave signal that are within a defined range are passed by thebandpass filter operation and other frequencies beyond the defined rangecan be filtered or attenuated by the bandpass filter operation.

As one example, pattern 606 may facilitate passing frequencies between5.5 gigahertz (GHz) and 6.5 GHz, while filtering or attenuatingfrequencies beyond the band of allowed frequencies such as those below5.5 GHz or above 6.5 GHz. It is appreciated that the defined range offrequencies that are passed can have a band width of approximately oneGHz or some other value depending on the geometry of pattern 606. Thisband of defined frequencies that are passed, having a width of one GHzor some other width, can be situated substantially anywhere in themicrowave spectrum, which is typically between about 300 megahertz (MHz)and 300 GHz. However, for certain applications used in conjunction withquantum computing architectures, filtering or attenuating frequencieswithin the ranges of between about one GHz and about 10 GHz can be ofmore significance. For instance, passing frequencies (while attenuatingfrequencies outside the range) within the defined ranges between about4.5 GHz to about 5.5 GHz, between about 5.5 GHz to about 6.5 GHz,between about 6.5 GHz to about 7.5 GHz, and so on can be representativeof a typical microwave filter.

As has been discussed, cryogenic microwave filter 600 can havesignificant advantages over other filter devices, particularly withregard to reducing Kapitza resistance and improving thermalization. Theinventors have identified that Kapitza resistance can be reduced byincreasing the surface contact area between substrate 602 and conductiveline 604, techniques for which are detailed below. The inventors havefurther identified that improved thermalization can be realized byselecting materials for cryogenic microwave filter 600 that have a veryhigh thermal conductivity, which can, e.g., improve the efficacytransferring hot electrons away from conductive line 604. As detailedabove, such can be in connection with a material selected for substrate602, in which the selected material has a thermal conductivity that isabove about 200 (or some other suitable value) W/m-K, with materialssuch as sapphire and diamond serving as representative examples. It isfurther appreciated that materials for conductive line 604 can beselected according to high thermal conductivity properties as well, withsome examples given below.

In addition to improving thermalization of conductive line 604, e.g., byincreasing thermal conductivity of the materials used in cryogenicmicrowave filter 600, Kapitza resistance can be reduced as well. Forexample, consider again boundary interface 506 of FIG. 5 , noting thatone or more similar boundary interfaces can exist between substrate 602and conductive line 604. While the interface between two differentmaterials might be represented as a smooth interface, at microscopicscales, the two materials may not be flush across the entire interface,resulting in reduced surface contact area between the two differentmaterials at the boundary interface. This reduced surface contact arearepresents a technological problem because such results in higherKapitza resistance or a higher ΔT.

The inventors have observed that both ΔT and Kapitza resistance can bereduced by increasing the surface contact area between conductive line604 and substrate 602 and have further determined that such can beaccomplished in distinct ways. For example, conductive line 604 can beconstructed or formed in such a way that contact at the boundaryinterface is more flush. As another example, the pressure at theboundary interface can be increased, resulting in more surface contactarea.

A technique that can be employed to advantageously leverage bothtechniques can be to sinter conductive line 604. In other words,conductive line 604 can comprise a conductive material that has beensintered in the recesses of substrate 602. Additional informationregarding sintering techniques can be found with reference to FIG. 10 .However, it is understood that by sintering conductive line 604, surfacecontact area at the boundary interface between two materials can beincreased, due in part to both creating a better “fit” with the surfaceof substrate 602 and by exhibiting increased pressure at the interfacethat tends to smooth out microscopic imperfections where contact mightotherwise not exist.

As can be further observed from pattern 606 that is representative of apattern for conductive line 604, various operations of the filter can beperformed by measuring radio frequency (RF) signals. Because conductiveline 604 is discontinuous or segmented, DC measurements may not be fullysupported. Such is not necessarily a drawback because qubits typicallyoperate at high frequencies (e.g., above 1 GHz) and DC measurements arenot used very often for such applications. Moreover, given that DCsignals can deliver low frequency noise that can negatively impactqubits, blocking DC signals can be beneficial.

Referring now to FIG. 7 , an example housing 700 for the cryogenicmicrowave filter 600 in accordance with one or more embodiments.Repetitive description of like elements employed in other embodimentsdescribed herein is omitted for sake of brevity. Housing 700 can encaseall or a portion of other components of cryogenic microwave filter 600.Housing 700 can comprise housing material 702 that can have variousadvantageous properties. For example, in some embodiments, housingmaterial 702 can be formed of an oxygen-free material. In someembodiments, housing material 702 can be electrolytic copper or similar.In some embodiments, housing material 702 can shield elements of acryogenic microwave filter (e.g., cryogenic microwave filter 600) frommicrowave noise, which can provide further improved performance.

As illustrated by grooves 704, housing 700 can be configured to coupleto refrigerator plates or other cryogenic elements that facilitate atransfer of thermal energy away from housing 700 or that operate as athermal sink. In some embodiments, housing 700 can be coupled to anelectrical ground, as illustrated by reference numeral 706. Furtherstill, housing 700 can be integrated into a suitable quantum computingarchitecture, such as being incorporated into a qubit housing.Connectors 708 can be single pole or high-density microwave connectorssuch as, e.g., SMP, SMA, Ardent, and so forth. In some embodiments,connectors 708 on both ends of housing 700 or cryogenic microwave filter600 can have the same gender (e.g., both male or both female). Such aconfiguration can reduce the number of connections on the qubit controllines, resulting in a reduced number of reflection points and, hence,improved performance.

FIGS. 8-10 illustrate a process by which a suitable thermal decouplingproduct can be produced in accordance with one or more embodiments.Repetitive description of like elements employed in other embodimentsdescribed herein is omitted for sake of brevity. In some embodiments,the thermal decoupling product can be representative of thermaldecoupling device 200 of FIG. 2 . In some embodiments, the thermaldecoupling product can be representative of a portion of thermallydecoupled cryogenic microwave filter device 300 or cryogenic microwavefilter 600. In FIGS. 8-10 , thermal decoupling product is show as across-section view being depicted at various stages of the process beingillustrated.

In that regard, FIG. 8 illustrates forming, e.g., by a fabricationdevice, dielectric 800. The fabrication device can be controlled bycomputing elements that comprise a processor and a memory that storesexecutable instructions that, when executed by the processor, facilitateperformance of operations. Examples of said processor and memory, aswell as other suitable computer or computing-based elements, can befound with reference to FIG. 15 .

In some embodiments, dielectric material 800 can be a substrate such assubstrate 602. For example, dielectric material 800 can operate as anelectrical insulator and a thermal conductor at cryogenic temperaturesbelow about 77 K. Dielectric material 800 can comprise a material havinga thermal conductivity that is above about 200 W/m-K at 77 K. It isunderstood that the thermal conductivity selected to satisfy aparticular application can depend on the application, so other thermalconductivity values can be selected, depending on the application orimplementation. For instance, for a different application, the materialof dielectric material 800 can be selected to have a thermalconductivity that is, e.g., above 1000 W/m-K at a temperature of 77 K,above 1000 W/m-K at a temperature of 20 K, above 20 W/m-K at atemperature of 10 K, and above 10 W/m-K at a temperature of 4 K, or anysuitable thermal conductivity value at any cryogenic temperature. TableI above, demonstrates that these example thermal conductivity values atthe various temperatures readily distinguish from commonly useddielectrics such as alumina. As discussed, selecting a material with anappropriately high thermal conductivity can significantly reduce Kapitzaresistance and significantly reduce the temperature drop, ΔT, at theboundary interface.

FIG. 9 illustrates forming, e.g., by the fabrication device, channels indielectric material 800 in accordance with one or more embodiments.Repetitive description of like elements employed in other embodimentsdescribed herein is omitted for sake of brevity. For example, thefabrication device can form a channel 900A and a channel 900B. Channel900A can be separated from channel 900B by wall 902 of the dielectricmaterial 800. In some embodiments, a pattern of the channels can beconfigured as a function of a filter operation for electromagneticradiation having frequencies within a microwave spectrum, such asbetween 300 MHz and 300 GHz. A representative example (shown from anoverhead view) of this pattern that can provide such behavior can bepattern 606. Thus, in addition to channels 900A and 900B beingdiscontinuous and separated by wall 902, in some embodiments, channels900A and 900B can be representative of a cross-section of the pattern606. Channels 900A and 900B can be created by pattern and etchingtechniques or any other suitable technique.

FIG. 10 illustrates conductive line 1000 formed in channels 900A and900B in accordance with one or more embodiments. Repetitive descriptionof like elements employed in other embodiments described herein isomitted for sake of brevity. For example, the fabrication device canform a conductive line comprising a first segment formed in channel 900Aand a second segment formed in channel 900B. The first segment ofconductive line 1000 can be separated from the second segment by wall902. Wall 902 can be configured to allow propagation of a microwavesignal (or a signal with sufficiently excited electrons) between thefirst segment and the second segment. Further, wall 902 can reduce heatflow between the first segment and the second segment of conductive line1000.

In some embodiments, conductive line 1000 can be formed of a sinteredconductive material. For example, conductive line 1000 can result fromsintering, e.g., by the fabrication device, a conductive material inchannels 900A and 900B. Additional detail relating to sintering can befound in connection with FIG. 13 .

It is understood that various boundary interfaces 1002 can exist betweenconductive line 1000 and dielectric material 800. As has been described,dielectric material 800 can comprise a material be selected to have veryhigh thermal conductivity. Likewise, a conductive material having highthermal conductivity can be selected in connection with conductive line1000. Using materials with high thermal conductivity can improvethermalization of the conductive line, thereby improving the performanceof the cryogenic microwave filter product. Furthermore, by sintering theconductive material, surface contact area can be increased at boundaryinterfaces 1002, which can reduce Kapitza resistance and further improveperformance in cryogenic environments.

FIGS. 11-14 illustrate various methodologies in accordance with thedisclosed subject matter. While, for purposes of simplicity ofexplanation, the methodologies are shown and described as a series ofacts, it is to be understood and appreciated that the disclosed subjectmatter is not limited by the order of acts, as some acts can occur indifferent orders and/or concurrently with other acts from that shown anddescribed herein. For example, those skilled in the art will understandand appreciate that a methodology could alternatively be represented asa series of interrelated states or events, such as in a state diagram.Moreover, not all illustrated acts need occur to implement a givenmethodology in accordance with the disclosed subject matter.Additionally, it should be further appreciated that the methodologiesdisclosed hereinafter and throughout this specification are capable ofbeing stored on an article of manufacture to facilitate transporting andtransferring such methodologies to computers.

FIG. 11 illustrates a flow diagram 1100 of an example, non-limitingmethod for fabricating a thermal decoupling device in accordance withone or more embodiments. Repetitive description of like elementsemployed in other embodiments described herein is omitted for sake ofbrevity. At reference numeral 1102, a fabrication device can formdiscontinuous channels in a dielectric. The discontinuous channels canhave a pattern comprising a first channel that is separated from asecond channel by a wall of the dielectric material.

At reference numeral 1104, the fabrication device can form a conductiveline in the discontinuous channels of the dielectric material. Theconductive line can comprise a first segment and a second segment thatare separated by the wall. The wall can facilitate propagation of amicrowave signal between the first segment and the second segment of theconductive line and can reduce heat flow between the first segment andthe second segment of the conductive line. In some embodiments, theforming the conductive line can comprise sintering a conductive materialin the discontinuous channels.

FIG. 12 illustrates a flow diagram 1200 of an example, non-limitingmethod for fabricating a thermally decoupled cryogenic microwave filterin accordance with one or more embodiments. Repetitive description oflike elements employed in other embodiments described herein is omittedfor sake of brevity. At reference numeral 1202, a fabrication device canform a dielectric that operates as an electrical insulator and a thermalconductor at cryogenic temperatures below about 77 K. In that regard,the dielectric can comprise a material having a thermal conductivitythat is above about 200 W/m-K at 77 K. By selecting the material to havea thermal conductivity above the designated threshold (in this caseabove about 200 W/m-K at 77 K), heat exchange between the conductiveline and the dielectric can be improved, which can improve theperformance of the cryogenic microwave filter when operating in very lowtemperature environments. Suitable examples of the material can includea sapphire material, a diamond material, or others.

At reference numeral 1204, the fabrication device can form discontinuouschannels in the dielectric. The discontinuous channels can be formed ina pattern that facilitates a filter operation on a microwave signalpropagated in the cryogenic environment. The discontinuous channels cancomprise a first channel and a second channel separated by a wall of thedielectric. Generally, a microwave signal is characterized as a signalhaving a frequency in a range between about 300 MHz and about 300 GHz.In some embodiments, the wall can have dimensions determined topropagate the microwave signal based on the microwave signal having afrequency that is above about one GHz.

At reference numeral 1206, the fabrication device can form a conductiveline in the discontinuous channels of the dielectric material. Theconductive line can comprise a first segment and a second segment thatare separated by the wall. The wall can facilitate propagation of amicrowave signal between the first segment and the second segment andcan reduce heat flow between the first segment and the second segment ofthe conductive line. By reducing heat flow between the first and secondsegments, thermal noise in the vicinity of the conductive line can bereduced, which can result in an improved signal.

As noted, this conductive line can operate as a microwave filter basedon the geometry of the channels. In some embodiments, the forming theconductive line can comprise sintering a conductive material in thediscontinuous channels. It is further noted that by sintering theconductive material, the resultant sintered conductive line can havereduced Kapitza resistance at the boundary interface(s) between theconductive line and the dielectric. This reduced Kapitza resistance canbe due in part to an increased surface contact area at the boundaryinterface(s) resulting from the sintering process.

FIG. 13 illustrates a flow diagram 1300 of an example, non-limitingmethod for sintering a conductive material in accordance with one ormore embodiments. Repetitive description of like elements employed inother embodiments described herein is omitted for sake of brevity. Atreference numeral 1302, fabrication device can deposit a powdered formof the conductive material in the recess of the substrate. The powderedform of the conductive material can be one that is selected to forexceptional thermal conductivity properties, which, as detailed inconnection with the material of the substrate can improve theperformance of the filter at low temperatures by reducing thetemperature drop at the boundary of the conductive line and thesubstrate. In some embodiments, the powdered form of the conductivematerial can be one of powdered gold, powdered copper, powdered silver,and powdered aluminum.

At reference numeral 1304, the fabrication device can expose thepowdered form of the conductive material to a sintering environment orsintering conditions. The sintering environment or conditions can becharacterized by a define temperature and a defined pressure that areselected to coalesce the powdered form of the conductive material to theconductive line without liquefying the conductive material. By employinga sintering technique in connection with the conductive line, highersurface contact area can be achieved between the dielectric and theconductive line, which can operate to reduce Kapitza resistance at lowtemperatures, and thus improve performance of the cryogenic microwavefilter at low temperatures.

Turning now to FIG. 14 , a flow diagram 1400 if illustrated of anexample, non-limiting method for fabricating a housing for a cryogenicmicrowave filter in accordance with one or more embodiments. Repetitivedescription of like elements employed in other embodiments describedherein is omitted for sake of brevity. At reference numeral 1402, thefabrication device can form or assemble a housing for the cryogenicmicrowave filter. The housing can be configured to couple torefrigerator plates that operate as a thermal sink.

At reference numeral 1404, the fabrication device can form or assembleconnectors. The connectors can couple to the conductive line at opposingends of the cryogenic microwave filter. In some embodiments, theconnectors can share a common gender type. For example, the connectorsat both ends of the filter can both be male type connectors or can bothbe female type connectors. An advantage that can be realized by such anarrangement can be that the number of connections on the qubit controllines can be reduced, which can result in a reduced number of reflectionpoints. As such, cleaner microwave control pulses can be provided andperformance of the filter can be improved.

At reference numeral 1406, the fabrication device can form the housingof a housing material that is selected to improve thermalization as wellas potentially shield filter elements from noise. In some embodiments,the housing material can be an oxygen-free material. In someembodiments, the housing material can be electrolytic copper.

It is understood that the present invention can be a system, a method,and/or a product form by a specified process. Certain technicalapplications of the invention can be provided by a computer programproduct at any possible technical detail level of integration. Thecomputer program product can include a computer readable storage medium(or media) having computer readable program instructions thereon forcausing a processor to carry out aspects of the present invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium can be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network can comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention can be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, configuration data for integrated circuitry, oreither source code or object code written in any combination of one ormore programming languages, including an object oriented programminglanguage such as Smalltalk, C++, or the like, and procedural programminglanguages, such as the “C” programming language or similar programminglanguages. The computer readable program instructions can executeentirely on the user's computer, partly on the user's computer, as astand-alone software package, partly on the user's computer and partlyon a remote computer or entirely on the remote computer or server. Inthe latter scenario, the remote computer can be connected to the user'scomputer through any type of network, including a local area network(LAN) or a wide area network (WAN), or the connection can be made to anexternal computer (for example, through the Internet using an InternetService Provider). In some embodiments, electronic circuitry including,for example, programmable logic circuitry, field-programmable gatearrays (FPGA), or programmable logic arrays (PLA) can execute thecomputer readable program instructions by utilizing state information ofthe computer readable program instructions to personalize the electroniccircuitry, in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions can be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create ways forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionscan also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions can also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams can represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the blocks can occur out of theorder noted in the Figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks cansometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

In connection with FIG. 15 , the systems and processes described belowcan be embodied within hardware, such as a single integrated circuit(IC) chip, multiple ICs, an application specific integrated circuit(ASIC), or the like. Further, the order in which some or all of theprocess blocks appear in each process should not be deemed limiting.Rather, it should be understood that some of the process blocks can beexecuted in a variety of orders, not all of which can be explicitlyillustrated herein.

With reference to FIG. 15 , an example environment 1500 for implementingvarious aspects of the claimed subject matter includes a computer 1502.The computer 1502 includes a processing unit 1504, a system memory 1506,a codec 1535, and a system bus 1508. The system bus 1508 couples systemcomponents including, but not limited to, the system memory 1506 to theprocessing unit 1504. The processing unit 1504 can be any of variousavailable processors. Dual microprocessors and other multiprocessorarchitectures also can be employed as the processing unit 1504.

The system bus 1508 can be any of several types of bus structure(s)including the memory bus or memory controller, a peripheral bus orexternal bus, or a local bus using any variety of available busarchitectures including, but not limited to, Industrial StandardArchitecture (ISA), Micro-Channel Architecture (MSA), Extended ISA(EISA), Intelligent Drive Electronics (IDE), VESA Local Bus (VLB),Peripheral Component Interconnect (PCI), Card Bus, Universal Serial Bus(USB), Advanced Graphics Port (AGP), Personal Computer Memory CardInternational Association bus (PCMCIA), Firewire (IEEE 1394), and SmallComputer Systems Interface (SCSI).

The system memory 1506 includes volatile memory 1510 and non-volatilememory 1512, which can employ one or more of the disclosed memoryarchitectures, in various embodiments. The basic input/output system(BIOS), containing the basic routines to transfer information betweenelements within the computer 1502, such as during start-up, is stored innon-volatile memory 1512. In addition, according to present innovations,codec 1535 can include at least one of an encoder or decoder, whereinthe at least one of an encoder or decoder can consist of hardware,software, or a combination of hardware and software. Although, codec1535 is depicted as a separate component, codec 1535 can be containedwithin non-volatile memory 1512. By way of illustration, and notlimitation, non-volatile memory 1512 can include read only memory (ROM),programmable ROM (PROM), electrically programmable ROM (EPROM),electrically erasable programmable ROM (EEPROM), Flash memory, 3D Flashmemory, or resistive memory such as resistive random access memory(RRAM). Non-volatile memory 1512 can employ one or more of the disclosedmemory devices, in at least some embodiments. Moreover, non-volatilememory 1512 can be computer memory (e.g., physically integrated withcomputer 1502 or a mainboard thereof), or removable memory. Examples ofsuitable removable memory with which disclosed embodiments can beimplemented can include a secure digital (SD) card, a compact Flash (CF)card, a universal serial bus (USB) memory stick, or the like. Volatilememory 1510 includes random access memory (RAM), which acts as externalcache memory, and can also employ one or more disclosed memory devicesin various embodiments. By way of illustration and not limitation, RAMis available in many forms such as static RAM (SRAM), dynamic RAM(DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM),and enhanced SDRAM (ESDRAM) and so forth.

Computer 1502 can also include removable/non-removable,volatile/non-volatile computer storage medium. FIG. 15 illustrates, forexample, disk storage 1514. Disk storage 1514 includes, but is notlimited to, devices like a magnetic disk drive, solid state disk (SSD),flash memory card, or memory stick. In addition, disk storage 1514 caninclude storage medium separately or in combination with other storagemedium including, but not limited to, an optical disk drive such as acompact disk ROM device (CD-ROM), CD recordable drive (CD-R Drive), CDrewritable drive (CD-RW Drive) or a digital versatile disk ROM drive(DVD-ROM). To facilitate connection of the disk storage devices 1514 tothe system bus 1508, a removable or non-removable interface is typicallyused, such as interface 1516. It is appreciated that storage devices1514 can store information related to a user. Such information might bestored at or provided to a server or to an application running on a userdevice. In one embodiment, the user can be notified (e.g., by way ofoutput device(s) 1536) of the types of information that are stored todisk storage 1514 or transmitted to the server or application. The usercan be provided the opportunity to opt-in or opt-out of having suchinformation collected or shared with the server or application (e.g., byway of input from input device(s) 1528).

It is to be appreciated that FIG. 15 describes software that acts as anintermediary between users and the basic computer resources described inthe suitable operating environment 1500. Such software includes anoperating system 1518. Operating system 1518, which can be stored ondisk storage 1514, acts to control and allocate resources of thecomputer system 1502. Applications 1520 take advantage of the managementof resources by operating system 1518 through program modules 1524, andprogram data 1526, such as the boot/shutdown transaction table and thelike, stored either in system memory 1506 or on disk storage 1514. It isto be appreciated that the claimed subject matter can be implementedwith various operating systems or combinations of operating systems.

A user enters commands or information into the computer 1502 throughinput device(s) 1528. Input devices 1528 include, but are not limitedto, a pointing device such as a mouse, trackball, stylus, touch pad,keyboard, microphone, joystick, game pad, satellite dish, scanner, TVtuner card, digital camera, digital video camera, web camera, and thelike. These and other input devices connect to the processing unit 1504through the system bus 1508 via interface port(s) 1530. Interfaceport(s) 1530 include, for example, a serial port, a parallel port, agame port, and a universal serial bus (USB). Output device(s) 1536 usesome of the same type of ports as input device(s) 1528. Thus, forexample, a USB port can be used to provide input to computer 1502 and tooutput information from computer 1502 to an output device 1536. Outputadapter 1534 is provided to illustrate that there are some outputdevices 1536 like monitors, speakers, and printers, among other outputdevices 1536, which require special adapters. The output adapters 1534include, by way of illustration and not limitation, video and soundcards that provide a way of connection between the output device 1536and the system bus 1508. It should be noted that other devices orsystems of devices provide both input and output capabilities such asremote computer(s) 1538.

Computer 1502 can operate in a networked environment using logicalconnections to one or more remote computers, such as remote computer(s)1538. The remote computer(s) 1538 can be a personal computer, a server,a router, a network PC, a workstation, a microprocessor based appliance,a peer device, a smart phone, a tablet, or other network node, andtypically includes many of the elements described relative to computer1502. For purposes of brevity, only a memory storage device 1540 isillustrated with remote computer(s) 1538. Remote computer(s) 1538 islogically connected to computer 1502 through a network interface 1542and then connected via communication connection(s) 1544. Networkinterface 1542 encompasses wire or wireless communication networks suchas local-area networks (LAN) and wide-area networks (WAN) and cellularnetworks. LAN technologies include Fiber Distributed Data Interface(FDDI), Copper Distributed Data Interface (CDDI), Ethernet, Token Ringand the like. WAN technologies include, but are not limited to,point-to-point links, circuit switching networks like IntegratedServices Digital Networks (ISDN) and variations thereon, packetswitching networks, and Digital Subscriber Lines (DSL).

Communication connection(s) 1544 refers to the hardware/softwareemployed to connect the network interface 1542 to the bus 1508. Whilecommunication connection 1544 is shown for illustrative clarity insidecomputer 1502, it can also be external to computer 1502. Thehardware/software necessary for connection to the network interface 1542includes, for exemplary purposes only, internal and externaltechnologies such as, modems including regular telephone grade modems,cable modems and DSL modems, ISDN adapters, and wired and wirelessEthernet cards, hubs, and routers.

While the subject matter has been described above in the general contextof computer-executable instructions of a computer program product thatruns on a computer and/or computers, those skilled in the art willrecognize that this disclosure also can or can be implemented incombination with other program modules. Generally, program modulesinclude routines, programs, components, data structures, etc. thatperform particular tasks and/or implement particular abstract datatypes. Moreover, those skilled in the art will appreciate that theinventive computer-implemented methods can be practiced with othercomputer system configurations, including single-processor ormultiprocessor computer systems, mini-computing devices, mainframecomputers, as well as computers, hand-held computing devices (e.g., PDA,phone), microprocessor-based or programmable consumer or industrialelectronics, and the like. The illustrated aspects can also be practicedin distributed computing environments where tasks are performed byremote processing devices that are linked through a communicationsnetwork. However, some, if not all aspects of this disclosure can bepracticed on stand-alone computers. In a distributed computingenvironment, program modules can be located in both local and remotememory storage devices.

As used in this application, the terms “component,” “system,”“platform,” “interface,” and the like, can refer to and/or can include acomputer-related entity or an entity related to an operational machinewith one or more specific functionalities. The entities disclosed hereincan be either hardware, a combination of hardware and software,software, or software in execution. For example, a component can be, butis not limited to being, a process running on a processor, a processor,an object, an executable, a thread of execution, a program, and/or acomputer. By way of illustration, both an application running on aserver and the server can be a component. One or more components canreside within a process and/or thread of execution and a component canbe localized on one computer and/or distributed between two or morecomputers. In another example, respective components can execute fromvarious computer readable media having various data structures storedthereon. The components can communicate via local and/or remoteprocesses such as in accordance with a signal having one or more datapackets (e.g., data from one component interacting with anothercomponent in a local system, distributed system, and/or across a networksuch as the Internet with other systems via the signal). As anotherexample, a component can be an apparatus with specific functionalityprovided by mechanical parts operated by electric or electroniccircuitry, which is operated by a software or firmware applicationexecuted by a processor. In such a case, the processor can be internalor external to the apparatus and can execute at least a part of thesoftware or firmware application. As yet another example, a componentcan be an apparatus that provides specific functionality throughelectronic components without mechanical parts, wherein the electroniccomponents can include a processor or other embodiments to executesoftware or firmware that confers at least in part the functionality ofthe electronic components. In an aspect, a component can emulate anelectronic component via a virtual machine, e.g., within a cloudcomputing system.

In addition, the term “or” is intended to mean an inclusive “or” ratherthan an exclusive “or.” That is, unless specified otherwise, or clearfrom context, “X employs A or B” is intended to mean any of the naturalinclusive permutations. That is, if X employs A; X employs B; or Xemploys both A and B, then “X employs A or B” is satisfied under any ofthe foregoing instances. Moreover, articles “a” and “an” as used in thesubject specification and annexed drawings should generally be construedto mean “one or more” unless specified otherwise or clear from contextto be directed to a singular form. As used herein, the terms “example”and/or “exemplary” are utilized to mean serving as an example, instance,or illustration and are intended to be non-limiting. For the avoidanceof doubt, the subject matter disclosed herein is not limited by suchexamples. In addition, any aspect or design described herein as an“example” and/or “exemplary” is not necessarily to be construed aspreferred or advantageous over other aspects or designs, nor is it meantto preclude equivalent exemplary structures and techniques known tothose of ordinary skill in the art.

As it is employed in the subject specification, the term “processor” canrefer to substantially any computing processing unit or devicecomprising, but not limited to, single-core processors;single-processors with software multithread execution capability;multi-core processors; multi-core processors with software multithreadexecution capability; multi-core processors with hardware multithreadtechnology; parallel platforms; and parallel platforms with distributedshared memory. Additionally, a processor can refer to an integratedcircuit, an application specific integrated circuit (ASIC), a digitalsignal processor (DSP), a field programmable gate array (FPGA), aprogrammable logic controller (PLC), a complex programmable logic device(CPLD), a discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed herein. Further, processors can exploit nano-scalearchitectures such as, but not limited to, molecular and quantum-dotbased transistors, switches and gates, in order to optimize space usageor enhance performance of user equipment. A processor can also beimplemented as a combination of computing processing units. In thisdisclosure, terms such as “store,” “storage,” “data store,” datastorage,” “database,” and substantially any other information storagecomponent relevant to operation and functionality of a component areutilized to refer to “memory components,” entities embodied in a“memory,” or components comprising a memory. It is to be appreciatedthat memory and/or memory components described herein can be eithervolatile memory or nonvolatile memory, or can include both volatile andnonvolatile memory. By way of illustration, and not limitation,nonvolatile memory can include read only memory (ROM), programmable ROM(PROM), electrically programmable ROM (EPROM), electrically erasable ROM(EEPROM), flash memory, or nonvolatile random access memory (RAM) (e.g.,ferroelectric RAM (FeRAM). Volatile memory can include RAM, which canact as external cache memory, for example. By way of illustration andnot limitation, RAM is available in many forms such as synchronous RAM(SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rateSDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), Synchlink DRAM (SLDRAM),direct Rambus RAM (DRRAM), direct Rambus dynamic RAM (DRDRAM), andRambus dynamic RAM (RDRAM). Additionally, the disclosed memorycomponents of systems or computer-implemented methods herein areintended to include, without being limited to including, these and anyother suitable types of memory.

What has been described above include mere examples of systems andcomputer-implemented methods. It is, of course, not possible to describeevery conceivable combination of components or computer-implementedmethods for purposes of describing this disclosure, but one of ordinaryskill in the art can recognize that many further combinations andpermutations of this disclosure are possible. Furthermore, to the extentthat the terms “includes,” “has,” “possesses,” and the like are used inthe detailed description, claims, appendices and drawings such terms areintended to be inclusive in a manner similar to the term “comprising” as“comprising” is interpreted when employed as a transitional word in aclaim. The descriptions of the various embodiments have been presentedfor purposes of illustration, but are not intended to be exhaustive orlimited to the embodiments disclosed. Many modifications and variationswill be apparent to those of ordinary skill in the art without departingfrom the scope and spirit of the described embodiments. The terminologyused herein was chosen to best explain the principles of theembodiments, the practical application or technical improvement overtechnologies found in the marketplace, or to enable others of ordinaryskill in the art to understand the embodiments disclosed herein.

What is claimed is:
 1. A method, comprising: forming, by a fabricationdevice, discontinuous channels in a dielectric, wherein thediscontinuous channels have a pattern comprising a first channel that isseparated from a second channel by a wall of the dielectric; andforming, by the fabrication device, a conductive line in thediscontinuous channels of the dielectric material, wherein theconductive line comprises a first segment and a second segment that areseparated by the wall that facilitates propagation of a microwave signalbetween the first segment and the second segment and reduces heat flowbetween the first segment and the second segment of the conductive line,wherein the forming the conducting line comprises coalescing a powderedform of a conductive material in the discontinuous channel to theconductive line without liquefying the conductive material.
 2. Themethod of claim 1, wherein the forming the conductive line alsocomprises sintering the conductive material in the discontinuouschannels.
 3. The method of claim 2, wherein the sintering the conductivematerial comprises: depositing, by the fabrication device, the powderedform of the conductive material in the discontinuous channels.
 4. Themethod of claim 3, wherein the sintering the conductive material furthercomprises: exposing, by the fabrication device, the powdered form of theconductive material to a sintering environment characterized by adefined temperature and a defined pressure.
 5. The method of claim 1,wherein the first channel and the second channel are substantiallyparallel.
 6. A method, comprising: forming, by a fabrication device, adielectric that operates as an electrical insulator and a thermalconductor at cryogenic temperatures below about 77 degrees Kelvin (K),wherein the dielectric comprises a material having a thermalconductivity that is above about 200 watts per meter-Kelvin (W/m-K) at77 K; forming, by the fabrication device, discontinuous channels in thedielectric, wherein the discontinuous channels are formed in a patternthat facilitates a filter operation on a microwave signal propagated ina cryogenic environment and the discontinuous channels comprise a firstchannel and a second channel separated by a wall of the dielectric;sintering, by the fabrication device, a conductive material in thediscontinuous channels having the pattern, resulting in a conductiveline comprising a first segment and a second segment that are separatedby the wall that facilitates propagation of the microwave signal throughthe conductive line and reduces heat flow between the first segment andthe second segment of the conductive line; and assembling, by thefabrication device, a housing, wherein the housing couples torefrigerator plates that facilitate a transfer of thermal energy awayfrom the housing.
 7. The method of claim 6, wherein the forming thediscontinuous channels comprises forming the first channel and thesecond channel separated by the wall having dimensions determined topropagate the microwave signal based on the microwave signal having adefined frequency.
 8. The method of claim 7, wherein the definedfrequency is above about one gigahertz (GHz).
 9. A process, comprising:forming, by a fabrication device, a first channel that is separated froma second channel by a wall of a dielectric material; forming, by thefabrication device, a conductive line comprising a first segment, formedin the first channel, and a second segment, formed in the secondchannel, separated by the wall, wherein the wall allows propagation of amicrowave signal between the first segment and the second segment andreduces heat flow between the first segment and the second segment ofthe conductive line; and assembling, by the fabrication device, ahousing, wherein the housing is configured to couple to refrigeratorplates that facilitate a transfer of thermal energy away from thehousing.
 10. A thermal decoupling product formed by a process,comprising: forming, by a fabrication device, a first channel that isseparated from a second channel by a wall of a dielectric material;forming, by the fabrication device, a conductive line comprising a firstsegment, formed in the first channel, and a second segment, formed inthe second channel, separated by the wall, wherein the wall allowspropagation of a microwave signal between the first segment and thesecond segment and reduces heat flow between the first segment and thesecond segment of the conductive line; and assembling, by thefabrication device, a housing, wherein the housing is configured tocouple to refrigerator plates that facilitate a transfer of thermalenergy away from the housing.
 11. The thermo decoupling product of claim10, further comprising forming discontinuous channels, wherein theforming the discontinuous channels comprises forming the first channeland the second channel separated by the wall having dimensionsdetermined to propagate the microwave signal based on the microwavesignal having a defined frequency.
 12. The thermo decoupling product ofclaim 11, wherein the defined frequency is above about one gigahertz(GHz).
 13. The thermo decoupling product of claim 10, wherein the firstchannel and the second channel are substantially parallel.